1. Field of the Invention
The present invention relates to a matrix-addressed display device, such as an electroluminescent (EL) display device.
2. Related Arts
A typical matrix-addressed EL display device as shown in FIG. 11, has a glass substrate 1 on which a stack of lower electrodes 2, a first insulating layer 3, a luminescent layer 4, a second insulating layer 5, and upper electrodes (back electrodes) 6 are formed, in that order. The lower and back electrodes 2 and 6 are data electrodes and scanning electrodes, respectively, and are orthogonally disposed to each other. Each lower electrode 2 has a strip-like shape with a terminal 7a at an end thereof. Each back electrode 6 has a strip-like shape with a terminal 7b at an end thereof. The terminals 7a and 7b of the lower and back electrodes 2 and 6 are arranged on at least two side of the glass substrate 1.
The areas where the terminals 7a and 7b are formed cannot function as display areas. Therefore, forming the terminals 7a and 7b on multiple sides of the glass substrate 1 requires a larger size of the EL display device. To solve this problem, Japanese Utility Model Publication No. 4-43995 proposes a matrix-addressed EL display device having through-holes, which are formed in non-intersecting portions between back electrodes and lower electrodes and which penetrate a luminescent layer and the like interposed to permit communication between the back electrodes and the lower electrodes. The EL display device further has lower electrode leading strips formed on the same plane as the back electrodes between the back electrodes adjacent to each other and electrically connected to the lower electrodes through the through-holes.
In the above-mentioned EL display device, however, forming the through-holes on the non-intersecting portions (non-pixel portions) between the lower and back electrodes gives rise to the following problems. For example, the manufacturing process becomes complicated, and the manufacturing costs are increased. In addition, because the lower electrode leading strips are formed between the back electrodes adjacent to each other, it is difficult to obtain a sufficient width lower electrode leading strips. Especially when the lower electrode leading strips are made of optically transparent material, the insufficient width of the lower electrode leading strips causes the problem that the wire resistance of each lower electrode leading strip increases.
Japanese Patent Application Laid Open No. 2-91618 discloses a matrix-addressed liquid crystal display device in which one set of X and Y electrodes, corresponding to back and lower electrodes, are electrically connected to leading wires which extend from portions thereof, corresponding to non-pixel portions, in parallel with another of the sets of the X and Y electrodes. In this case, there is a problem that the leading wires have to be connected to the one of the sets of X and Y electrodes at the portions corresponding to non-pixel portions of the liquid crystal display, thereby restricting the widths of the one of the sets of X and Y electrodes.